A printing apparatus which prints information such as a desired character or image on a sheet-like printing medium such as a paper sheet or film is widely used as an information output apparatus in a word processor, personal computer, facsimile apparatus, and the like.
Various methods are known as printing methods adopted in the printing apparatus. Especially an inkjet method has recently received a great deal of attention because this method can realize noncontact printing on a printing medium such as a paper sheet, easily prints in color, and is quiet. Because of low cost and easy downsizing, a popular inkjet arrangement is a serial printing system in which a printhead for discharging ink in accordance with desired printing information is mounted and prints while the printhead is reciprocally scanned in a direction perpendicular to the convey direction of a printing medium such as a paper sheet.
In general, the inkjet printing apparatus clogs because ink attached to the discharge surface of the printhead thickens or dust attaches to the discharge surface upon the lapse of time. The inkjet printing apparatus must periodically receive recovery operation such as cleaning of the discharge surface of the printhead or suction of nozzles. For this purpose, the inkjet printing apparatus is generally configured to request a computer serving as a host device to transmit current time data, calculating the time elapsed after previous recovery operation on the basis of the received time data, and when the elapsed time exceeds a predetermined time, executing recovery operation (see, e.g., Japanese Patent Laid-Open No. 3-234544).
Along with the spread of digital cameras, camera-equipped cell phones, and the like, demands have recently arisen for printing data such as images stored in PDAs, cell phones, digital cameras, and the like. There is proposed a printing apparatus which is connected to such device to print. There is also proposed a printing apparatus which has a slot for inserting a storage medium such as a memory card and can print image data stored in the storage medium inserted into the slot.
When the host device is a computer, it can transmit current time data to a printing apparatus. When the host device is not a computer or image data stored in a storage medium inserted into a slot is to be printed, as described above, the printing apparatus must incorporate a timepiece means (timer) which counts the current time.
If the timer is incorporated, e.g., a coin type battery must be arranged to always operate the timer. Such battery has conventionally been soldered to the control board of the printing apparatus. Recently, an arrangement which allows easily removing a battery without disassembling the printing apparatus is required as measures for environmental issues and the like.
In the arrangement which allows easily removing a battery, if the user erroneously removes the battery or the printing apparatus is shocked, the battery may be temporarily electrically disconnected to stop power supply to the timer. In this case, the timer cannot accurately count the time, and the interval of recovery operation of the printhead is prolonged, degrading the printing image quality.
This problem is not limited to the inkjet printing apparatus, and is common to another type of printing apparatus whose printhead or printing portion must be periodically maintained.